6. Redundancy with NX3030 CPU
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Besides keeping the projects synchronized, the Project Synchronization will also avoid the Non-
Active CPU to assume superior states in relation to Starting in case the CRC is different or some
Online Change is to be executed in the Active CPU.
ATTENTION:
A project synchronization will have the same effect as a download in the Non-Active CPU. This
service isn’t executed if the automatic Project Synchronization Disabling, as it’s described on
Project section. No synchronization service between CPUA and CPUB works in case the
synchronism channels cables are inverted. E.g. to connect the NETA channel in the NETB channel
from CPUB and the NETB from the CPUA in the NETA in the CPUB.
ATTENTION:
In the update from the version 1.20 to later versions of MasterTool IEC XE, was done a modification
in the communication protocol between the synchronism channels. Therefore, is not possible to sync
data between two PLCs when one of the applications has been created in a version prior to 1.21 and
another application has been created in an equal or higher version. To be able to perform the
synchronization, you should perform the actions described at section Not Loading the Application at
Startup in the PLC with the oldest project. Doing this, the application will not be loaded, but, when
this PLC goes to Non-Configured state during the system initialization, the applications will be
synchronized automatically.
ATTENTION:
Before version 2.01 of MasterTool IEC XE, when sending the source code to the active CPU, the
Stand-by CPU went for Non-Configured state to sync it. However, to complete the synchronization
operation, the CPU remained in the state Non-Configured, being necessary to pass the CPU to
Stand-by status via STAND-BY button on the PX2612 or equivalent command. Starting with
version 2.0.1 the CPU that is in Stand-by will change your state to Not-Configured during the
synchronization process, but will return automatically when the sources are the same between the
two Half-Clusters
Project Synchronization Disabling
On Sporadic Synchronization Services through NETA and NETB section, applicative project and
archive project synchronization services were described. These services normally must be enabled,
and are useful when the project modifications can be downloaded on-line in the Active CPU and the
Stand-by CPU afterwards, automatically, through the synchronism channels NETA/NETB.
However, there are project modifications which can’t be downloaded on-line in any CPU, e.g. the
inclusion of modules in a PROFIBUS remote, or the inclusion of a new PROFIBUS remote. In these
cases, using the CPU and PROFIBUS network redundancy, such modifications can be made without
interrupting the process control. A procedure to accomplish this objective is described in the
Exploring the Redundancy for Off-Line downloading of Modifications without Interruption of the
Process control section.
In this procedure it’s necessary to disable temporarily the project synchronizations, allowing, for a
while, one CPU to operate with a project new version, while the other CPU still operates with the old
project version.
A NX3030 CPU has a register for Project Synchronization Disabling, nonvolatile, which allows the
disabling of the project application and project archive synchronization services. This register can be
adjusted using MasterTool. It’s enough to disable the project synchronization in one of the two CPUs
to guarantee it doesn’t work anymore.
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